/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: AlternativePattern.java,v 1.2.4.1 2005/09/01 09:18:46 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.GOTO;
import com.sun.org.apache.bcel.internal.generic.InstructionHandle;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
final class AlternativePattern extends Pattern {

  private final Pattern _left;
  private final Pattern _right;

  /**
   * Construct an alternative pattern. The method <code>setParent</code>
   * should not be called in this case.
   */
  public AlternativePattern(Pattern left, Pattern right) {
    _left = left;
    _right = right;
  }

  public void setParser(Parser parser) {
    super.setParser(parser);
    _left.setParser(parser);
    _right.setParser(parser);
  }

  public Pattern getLeft() {
    return _left;
  }

  public Pattern getRight() {
    return _right;
  }

  /**
   * The type of an '|' is not really defined, hence null is returned.
   */
  public Type typeCheck(SymbolTable stable) throws TypeCheckError {
    _left.typeCheck(stable);
    _right.typeCheck(stable);
    return null;
  }

  public double getPriority() {
    double left = _left.getPriority();
    double right = _right.getPriority();

    if (left < right) {
      return (left);
    } else {
      return (right);
    }
  }

  public String toString() {
    return "alternative(" + _left + ", " + _right + ')';
  }

  public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
    final InstructionList il = methodGen.getInstructionList();

    _left.translate(classGen, methodGen);
    final InstructionHandle gotot = il.append(new GOTO(null));
    il.append(methodGen.loadContextNode());
    _right.translate(classGen, methodGen);

    _left._trueList.backPatch(gotot);
    _left._falseList.backPatch(gotot.getNext());

    _trueList.append(_right._trueList.add(gotot));
    _falseList.append(_right._falseList);
  }
}
